Raman spectroscopy is a powerful tool for quantitative analysis of the composition and concentration of blood analytes within a sample, such as blood glucose 15 concentration. Raman spectroscopy is based on inelastic light scattering rather than absorption of light. Interactions between the incident photons and molecules in the sample result in scattering of light. Comparing with many other techniques, Raman is a sensitive and selective technique. It can measure glucose at a very low concentration in a test tube. However, when it comes to non-invasive measurement of glucose in human 20 body, the result is unreliable due to the variations and fluctuations in the subject's physiological state and other environmental factors. There have been many attempts to improve the sensitivity and accuracy of blood glucose measurement based on Raman system. Even though the best sensitivity achieved so far is getting close to 15 mg/dl in human body that can only be obtained after tedious calibration procedures associated 25 with multivariate analysis without specifying the origins of the variations in the Raman spectra. As a result, the stability of such calibration procedures and the robustness of such glucose predictions are often questionable.
Therefore, a better approach is called for to circumvent above-mentioned shortcomings.